"This other person then tried to help him out and pull him up back onto the platform in time before the train came, but it wasn’t in time and they both got hit. I believe it was pretty bad."

Another said: "They played the CCTV and you could see that the man dropped something down onto the track, a mobile phone or a wallet or something, and even though the train was coming he went down to try and get it.

"The other person who tried to help him was then hit as they were leaning over and trying to help him back up. But the train came along and hit them too. It was really tragic.

"It happened at the back of the platform, just as the train pulls in so maybe they didn’t realise how close the train was."

A BTP spokesman said: "Our officers were called to Old Street station at 12.22am on Sunday following reports of a person being struck by a train.

"On arrival officers discovered two men on the tracks with serious injuries.

"The men - one aged 32 from Manchester and the other aged 35 from London - were treated at the scene by colleagues from the London Ambulance Service and then taken to Royal Free Hospital in a critical condition.

Critical: The man who initially fell on the line remains in hospital fighting for his life (Image: Léonie Chao-Fong)

"The 35-year-old man from London died in hospital later that day.

"The 32-year-old from Manchester remains in a stable but critical condition.

"Officers are not treating the incident, which appears to be a tragic accident, as suspicious."

A Transport for London spokesman said: "At 00:21 hours on Sunday two men were involved in a collision with a train on the southbound track at Old Street station.

"Emergency services attended the scene and the men were taken to Royal Free Hospital.

"Police colleagues described the incident as non-suspicious, and we are working with them on a thorough investigation."